1. Field of the Invention
The present invention generally relates to hot runners and, particularly, to a hot runner used in a mold assembly.
2. Description of Related Art
Insert molding technology using molding machines is a popular molding method. A typical molding machine usually includes a hot runner, a male mold and a female mold. The male mold and the female mold define a mold cavity therebetween. The male mold has a passage defined therein, communicating with the mold cavity. The hot runner is inserted into the passage. Thus, melted plastic can be injected into the mold cavity through the hot runner.
To prevent the melted plastic from leaking out of a combining aperture between the hot runner and the passage, a vertical surface is formed on the outside of the hot runner. The vertical surface is an outer peripheral surface surrounding the longitudinal axis of the hot runner. Correspondingly, the passage has a cooperating surface. The vertical surface is tightly attached to the cooperating surface, thus preventing leakage of melted plastic.
However, after repeated usage, a gap may appear between the vertical surface and the cooperating surface because of abrasion, high temperature, and high pressure. Thus, melted plastic may leak to the outer surface of the hot runner, resulting in damaging other elements, i.e., the heating coil and the temperature-sensing equipment.
Thus, there is room for improvement within the art.